This invention relates generally to sighting or aiming devices and, more particularly, to a sighting device for firearms and the like which is useful in sighting under both bright and dim ambient light conditions.
A recognized problem in the sighting or aiming of firearms and other similar equipment is the difficulty encountered when attempting to use the equipment under varied ambient light conditions. For example, firearms frequently are equipped with so-called metallic sight pairs including a front blade sight that is mounted near the end of the barrel of the firearm, and a rear notch sight that is mounted in proximity to the chamber or cylinder of the firearm, closer to the shooter's eye. In sighting, the blade of the front blade sight is typically aligned and centered in the notch of the rear sight, with the target image positioned directly above the blade. Such metallic sight pairs are generally useful in moderate to bright ambient light conditions. In dim ambient light conditions, however, difficulty is typically encountered in discerning and locating the sights relatively to one another, particularly the front blade sight which is spaced farther from the shooter's eye.
While a wide variety of devices have been proposed heretofore to alleviate the above and related difficulties in sighting, few, if any, of these prior devices have encountered any significant degree of commercial acceptance. One class of prior devices is exemplified by those shown in U.S. Pat. Nos. 2,385,649; 3,678,590; 3,833,799; 3,994,072. As is evident from a review of these patents, these devices utilize an independent light source to illuminate one or more parts of the sighting equipment, and are designed to be attached to the firearm when use under low ambient light conditions is anticipated. Such devices are disadvantaged not only because of their relative complexity and high cost, but also because of their rather obtrusive and unconventional appearance when mounted to the firearm. As a result of this, such devices are typically attached and used only under the highly specialized condition of low ambient light, and rarely left on the firearm as a permanent fixture for use under any condition.
Another class of prior devices is exemplified by those shown in U.S. Pat. Nos. 1,292,211; 1,307,063; 2,246,174; 2,822,616; 2,987,821; 3,218,718; and 3,641,676. These devices utilize one or another form of a self-luminous substance, such as an iridescent, phosphorescent, fluorescent or radioluminescent material, that is painted or otherwise deposited on parts of the sight to illuminate them. While such devices are generally simplier and less expensive than the independently illuminated devices discussed above, they too are disadvantaged. Specifically, the self-luminous substance used in such devices can be scratched or can wear off the sight parts, or lose its light emitting capability, over time and in normal use of the firearm.
Still another class of prior sighting devices or aids is represented by U.S. Pat. Nos. 1,346,303; 2,706,335; 3,362,074; and 3,439,970. These devices utilize bodies of transparent material, such as optical grade glass or plastic, which are mounted as part of the sighting element and which are shaped and configured like prisms or lenses to collect, concentrate and/or focus ambient light so as to provide improved sighting conditions. Like the devices of the first class mentioned above, these devices are relatively expensive to make, and rather obtrusive and unconventional in appearance when mounted to a firearm. Further, like the devices of the second class mentioned above, they are relatively delicate due to their susceptibility to scratching, breakage and wear in normal use of the firearm. These factors have militated against the widespread acceptance of such devices for firearms and other such sighted equipment.